Computer-aided tracking, navigation, and motion teaching are important tasks in a wide range of applications, including surgery and factory automation. The prior art contains technology directed to the tasks of computer-aided tracking, navigation, and motion teaching. However, the prior art is deficient in several areas, as will be discussed in more detail hereinbelow. Arthroscopy is a minimally invasive surgical procedure used to decrease the necessary incision size for joint repair surgery. Large operative incisions are replaced by small portal incisions. While a 15-25 cm opening is necessary to fully expose the hip joint using traditional methods (Scuderi G R and Tria A J. MIS of the Hip and the Knee: A Clinical Perspective. Springer-Verlag: New York. 2004.), arthroscopy only requires two or three portals of approximately 6-7 mm (Safran M R, Stone D A, Zachazewski J. Instructions for Sports Medicine Patients. Elsevier Inc.: Philadelphia. 2003.). A long thin camera, called an arthroscope, is placed in one portal to display 44 the joint area that would otherwise require a full-size incision to expose. Additional portals are employed for the insertion of surgical tools. FIG. 1 illustrates a prior art arrangement for hip arthroscopy. As shown in FIG. 1, the surgeon navigates a surgical tool by using only camera images displayed on an operating room screen.
Arthroscopy was initially introduced as a diagnostic tool, but now has significant advantages for many joint repair procedures (See, for example, Villar R N. Hip Arthroscopy. Butterworth-Heinemann Ltd.: Oxford. 1992.). Advantages such as a faster recovery time, shorter hospital stay, less soft tissue trauma, less blood loss, and a lower incidence of infection make arthroscopic surgery more desirable than traditional full-incision operations (See, for example, Scuderi G R and Tria A J. MIS of the Hip and the Knee: A Clinical Perspective. Springer-Verlag: New York. 2004.). Hip arthroscopy can be used for removing loose bodies, smoothing rough bone surfaces, and trimming damaged or abnormal bone and tissue (See, for example, Safran M R, Stone D A, Zachazewski J. Instructions for Sports Medicine Patients. Elsevier Inc.: Philadelphia. 2003.). Also, minimally invasive treatment of early hip problems could decrease or delay the onset of other more serious hip conditions (See, for example, McCarthy J C, Noble P C, Schuck M R, Wright J, Lee J. The Role of Labral Lesions to Development of Early Degenerative Hip Disease. Clinical Orthopaedics and Related Research, 2001; 393:25-37; and Ganz R, Parvizi J, Beck M, Leunig M, Notzli H, Siebenrock K A. Femoroacetabular Impingement. Clinical Orthopaedics and Related Research. 2003; 417:112-120.).
Despite the benefits of arthroscopic surgery, arthroscopy is not as common in hip repair as in knee and shoulder repair. The hip joint introduces additional challenges for arthroscopy. For example, the hip joint is located deeper within the body than joints such as the knee or shoulder. Also, the ball and socket geometry of the joint provides a very tight working envelope. Finally, there are an increased number of surrounding muscles, ligaments, and neurovascular structures to consider in the case of the hip joint.
The challenges associated with the hip have created two particular obstacles for arthroscopic hip surgery: awareness of spatial orientation during joint navigation; and portal incision placement while avoiding damage to critical anatomical structures. Although the arthroscope allows the surgeon to observe the joint, extra skill is required to associate the camera image with the actual patient anatomy for navigation. This is a common problem for other minimally invasive surgeries including MIS hip replacement and laparoscopic procedures (See, for example, Scuderi G R and Tria A J. MIS of the Hip and the Knee: A Clinical Perspective. Springer-Verlag: New York. 2004.; and Schijven M, Jakimowicz J. Face-, expert, and referent validity of the Xitact LS500 Laparoscopy Simulator. Surgical Endoscopy. 2002; 16:1764-70.). Instrument placement is a critical step in establishing the desired arthroscope viewing area. Multiple arteries, veins, and nerves populate the area in which the portal incisions are placed. The surgeon's challenge is to create incisions that provide appropriate access to the joint, but do not harm the sciatic nerve, femoral artery, or femoral vein. The surgeons who perform this procedure rely heavily on intuition gained through experience to overcome these challenges.
Computer-aided tools are appearing more frequently to assist in medical procedures and as training simulators. For example, hip replacement systems enable the surgeon to place implants more accurately and consistently (See, for example, DiGioia A M, Simon D A, Jaramaz B, Blackwell M, Morgan F, O'Toole R V, Colgan B, Kischell E. HipNav: Pre-operative Planning and Intra-operative Navigational Guidance for Acetabular Implant Placement in Total Hip Replacement Surgery. In: Computer Assisted Orthopaedic Surgery Symposium; 1995 Nov. 30-Dec. 2; Bern, Switzerland; and Taylor R H, Mittelstadt B D, Paul H A, Hanson W, Kazanzides P, Zuhars J F, Williamson B, Musits B L, Glassman E, Bargar W L. An Image-Directed Robotic System for Precise Orthopaedic Surgery. IEEE Transactions on Robotics and Automation. 1994; 10(3):261-275.). A system for minimally invasive coronary bypass surgery assists with incision accuracy and visualization of the tool within the patient (See, for example, Chiu A M, Boyd D, Peters T M. 3-D Visualization for Minimally Invasive Robotic Coronary Artery Bypass (MIRCAB). In: 22nd Annual EMBS International Conference; 2000; Chicago Ill.). Training simulators are currently under research for procedures such as laparoscopic and minimally invasive heart surgery (See, for example, Schijven M, Jakimowicz J. Face-, expert, and referent validity of the Xitact LS500 Laparoscopy Simulator. Surgical Endoscopy. 2002; 16:1764-70; and Rotnes J S, Kaasa J, Westgaard G, Eriksen E M, Hvidsten P O, Strom K, Sorhus V, Halbwachs Y, Jakob O, Fosse E. Realism in surgical simulators with free-form geometric modeling. In: Lemke H U, Vannier M W, Inamura K, Farman A G, Doi K, editors. Computer Assisted Radiology and Surgery; 2001; Berlin, Germany. Elsevier; 2001. p. 997-1002.). While these and other tools have been introduced to supplement a surgeon's abilities, a similar tool for arthroscopic hip surgery does not exist. One embodiment of the present invention focuses on the particular issues of portal placement and instrument navigation in arthroscopic hip surgery.
Position tracking is also an important component of many other computer-aided surgical systems. Optical and electromagnetic systems are the most common types of tracking devices, but these systems have limitations. For instance, an optical system can lose information from its position sensors if the line of sight to the receiver is broken. Optical systems such as those provided by Northern Digital Inc. or Advanced Realtime Tracking (ART) are more accurate than electromagnetic systems for medical applications, but are relatively expensive (See, for example, Birkfellner W, Watzinger F, Wanschitz F, Ewers R, Bergmann H. Calibration of tracking Systems in a Surgical Environment. IEEE Transactions on Medical Imaging. 1998; 17(5):737-42; Advanced Realtime Tracking (homepage on the Internet). Mar. 25, 2005. Available from: http://www.ar-tracking.de/; Northern Digital Inc. (homepage on the Internet). Mar. 25, 2005. Available from: http://www.ndigital.com/certus.php). While less expensive, electromagnetic systems are susceptible to distortion or noise from other metallic objects or stray magnetic fields. More complex or hybrid systems which combine both technologies are currently under research (See, for example, Schwald B, Seibert H. Registration for a Hybrid Tracking System 40 for Medical Augmented Reality. Journal of WSCG. 2004; 12(1-3).).
Mechanical tracking systems avoid the occlusion and distortion issues, but few mechanical systems exist. The few available products, such as the Faro Arm (See, for example, Faro Technologies (homepage on the Internet). Feb. 18, 2006. Available from: http://www.faro.com/), are too large and heavy to be easily manipulated. Due to their associated problems, the existing tracking devices listed above have significant drawbacks.
Position tracking is also important in fields other than the medical field. For example, position tracking is important in many industrial applications. In particular, the manufacturing and assembly industries are using increasing numbers of robots and other computer controlled machines. These machines are often used in the space previously occupied by human workers. As a result, the robots must not only be “trained” to do the proper job, but they must be trained to do the proper job within certain constraints. For example, robots must often operate within a particular space, so as not to interfere with other robots, with human workers, or with other obstacles. The prior art process of teaching a robot is tedious and time consuming. As a result, the efficiencies of robots are slow to be realized or are not being realized to their full potential.
In other applications, position tracking is important for recreating objects, such as one of a kind objects handmade by skilled artisans. Thereafter, it may be necessary to translate the handmade objects into information that can be used by computer controlled manufacturing processes to manufacture the objects in large numbers, to create computer-generated images and models of the objects, or to otherwise analyze or work with the objects. Several processes exist for such tasks, although they typically require relatively large and bulky machines that do not work well with objects having hard to reach surfaces.
Accordingly, there is a need for improved apparatuses and methods for use with computer aided tools, particularly for position tracking although not limited thereto. Those and other advantages of the present invention will be described in more detail hereinbelow.